The 100mpg Axon city car

This is the Axon city car. It’s a British project in its early stages of development, whose creators claim they’ll produce a 100mpg (70g/km CO2) urban vehicle by 2011. The orange prototype body shell has been developed by Axon with Warwick University and has been aerodynamically optimised in the wind tunnel to make it as slippery as possible. It’s made of a strong, moulded carbonfibre composite and has plastic door panels, so it weighs only 400kg. The Axon doesn’t use any trick future technology, just a 500cc, twin-cylinder engine that’s been developed by engineering consultancy Ptech Engines. Originally, the twin-cylinder was developed for a hybrid version of the Smart car before Mercedes took over the project. Based at Snetterton, Ptech says the engine will meet Euro 5 emissions standards and promises it will be hassle-free to maintain. The unit only produces around 40bhp, but Axon is convinced this will be enough to keep pace with city traffic while delivering 100mpg and tax-free emissions. The project’s part-funded with government money, but it’ll be at least two years before the Axon reaches any kind of production reality. The next step is to homologate the Axon to reach European crash standards, which its makers are convinced it can achieve.

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Admirable 100mpg especially when we're all less concerned with the enviroment impact of our cars (which is 0.0002%) and concerned with fuel economy to avoid fuel tax (which is 300%).

It's interesting these hi-economy models all have bodies shaped like a wind tunnel test. Most would barely hit the 70mph requirement for aerodynamics to take any effect!

The carbon moulded body panels and 400kg weight is excellent too. But again I've just posted an American study that shows whatever benefits you gain in weight and fuel economy you lose in real world structural integrity and safety. It's estimated road deaths will increase so how you balance that against fuel economy is up to you!

It's interesting these hi-economy models all have bodies shaped like a wind tunnel test. Most would barely hit the 70mph requirement for aerodynamics to take any effect!

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To understand the effect of aerodynamics on energy loss, try riding a bicycle. For most vehicles aerodynamic drag overtakes the effects of rolling resistance on fuel consumption at about 25 mph. Any motorcyclist (particularly those without a fairing) will confirm that wind resistance isn't suddenly switched on at 70mph.

Hi-economy models also need to be low on mass too, since in real world journeys, not motor industry befuddled fuel consumption tests, most of the fuel consumed is being constantly radiated to the atmosphere by the brakes. The lower the mas being constantly accelerated and decelerated, the lower the energy consumption.

On the effect of mass on safety it's worth noting that as the car's mass reduces, the proportion of the crumple zone dedicated to cushioning the blow to the occupants increases. If you still think a car needs to be heavy to be safe, study some Formula 1 crashes. Taking the big is safe argument to it's logical conclusion means we all end up driving cars of infinite mass (I'll stick to loading up my bumpers with depleted uranium).

I think the time for this kind of vehicle is long overdue - what real progress has been made thus far since, say, the citroen AX ? Certainly not much in terms of fuel efficiency.

Jonnie, in principle I'd agree with the view aerodynamics take effect below 70mph because I've ridden a bicycle at 15-25mph and felt wind resistance build and had a few motorbikes and 'felt the force' begin at 45 to 50mph too. However in a larger car than this orange one here with more power (120-300bhp) wind resistance is incidental (statistically insignificant) below 70 on fuel economy.

When our puny human bodies pump out about 2bhp to push a bicycle a 30mph oncoming wind soon knocks the puff out of you. For a green eco-city car with 45 to 60bhp a head on wind may have some effect but not enough to justify expensive wind tunnel testing when your top speed is 80mph. The shaving of drag factors from .32cd down to .28 on a car has no effect on fuel economy below 70mph - you may as well try putting on go-faster stripes!

Again I'd agree with your 'lightness doesn't compromise safety' theory in principle. Porsche argued the original Boxster when launched had to have a long nose for crash safety because of criticism it didn't faithfully reproduce the short snout of the stunning concept car. Anyone who saw a BMW 3-Series going by with barely a 4" nose would wonder how far Porsche safety technology was behind BMW's!

The truth was the Boxster had a 911 chassis for cost saving reasons and they couldn't alter it for that reason alone. But although I agree F1 cars etc are light and capable similarly a heavier car employing the same technology will be even safer. There's no getting away from the fact heavier cars are safer if they use the same technology in the same clever way. And a 400kg car is never going to get close to a 1,200kg.

I'd also like to see them build a 400kg car with all the safety technology of say a Golf or Clio - ABS brakes and steering, dash and door side airbags, safety struts in the side doors etc. This 400kg orange has a lot of corners cut on safety.

The new Polo Bluemotion will do 75mpg and the Fox may hit 100mpg shortly so your dream for the 100mpg car is on the way even though it weighs a lot more than 400kg primarily according to car makers moans because of worldwide safety standards.

It's not really heavier cars as such that are safer, more larger cars. Making the car heavier means you've got more energy to dissipate in a crash, making it larger (longer) allows the energy to be dissipated over a longer period of time. The main safety 'benefit' of heavier cars is that they cause more damage to what they hit and thus come to a stop more slowly, be that another lighter car or a deformable object. Fine if you're in the heavier car, less good if you're not. I would be very interested to know how occupant safety varies with size and weight for otherwise similar cars in a two-vehicle crash. I suspect that a head-on crash between two heavy vehicles would greatly reduce the safety advantage they have relative to average vehicles.

I'm not sure how good an example F1 cars are - their safety comes from having a very strong tub and impact-absorbing barriers around the circuits. The drivers are also very tightly constrained compared to road cars. Two F1 cars having a head-on crash at 30mph could be more violent than two road cars having the same crash as there's not a lot of energy absorbing material between the drivers. F1 cars don't tend to run head on into other cars or brick walls though...

Making the passenger cell out of high strength, light weight (and very expensive) materials would help, as reducing the car's overall mass means there's less energy to be dissipated in the crumple zones. In turn this should mean the crumple zones themselves can be lighter (but not shorter as there's no getting away from the need to minimise deceleration rates), further reducing the mass of the car. Alternatively they could be engineered to withstand a greater impact, but would this come at the cost of harsher low-speed impacts?

Anyhow, I think it should be possible to make a light car that can withstand single-vehicle or lab-test crashes as well as a larger car, the problem comes in the real world when you start crashing into heavier vehicles.

Re: aerodynamics - if the car is intended for city use, then aerodynamics aren't especially significant. That doesn't mean aerodynamics aren't important for a vehicle with 40bhp - there are bonneville streamliners that do 180mph with that amount of power, aero drag is still the limiting factor. What I don't know is how much engineering effort is involved in getting a car design down to a Cd of ~0.3 in the first place. My gut feeling says it might be harder than you expect, in which case the wind tunnel testing would be justified. Anyone? For any car, shaving 0.01 off a Cd of around 0.3 is going to make a fairly negligible difference, there are greater gains to be had by reducing the overall Cd.A figure by reducing the frontal area.

FWIW the reynolds numbers of car and person sized objects are such that aero drag increases with the square of speed for all 'interesting' speeds, but at low speeds constant friction and rolling resistance losses are more significant.

Sorry guys, this looks like another load of junk funded by the UK government. It will never be built and if it is no-one will buy it. Old-tech engine rejected by Mercedes is not a good start. Being able to keep up with city centre traffic means it will do about 25 mph by my reckoning. As with obscenities like the G-wizz all normal safety considerations will be over-looked 'cos its GREEN. It will cost the earth - well compared to buying something sane like a 4 year old Astra diesel - and the company that sells it will be unable to supply parts and back up on any sort of normal service. It will just sell - assuming I'm wrong and the thing is actually built - to Guardianistas and weirdos who will do anything to polish their self-regarding eco credentials. Don't let's forget that the reverred Prius is one of the least green cars on the planet. Sorry, but if the great Gordon Murray can't get a new eco-car off the ground (last heard of 07/07) I don't think Warwick University and two companies no-one has ever heard of are going to succeed. Diesel technology with stop start is the way to go via major producers.

John(faganwilliams), you have it nailed. Jesus what a lash-up. Looks like the front of the old Citroen AX mated to the back of a Prius and then shrunk. What a joke putting spats(covers) over the rear wheelarches and then having panel gaps - especially door leading-edge to wing panel - the likes of which haven't been seen in the car industry since BL in the 1970s and all the turbulence and drag kicked up by them.

Would seem that Axon Automotive Ltd's single claim to fame rests on recycling old carbon fibre, which they demoed on the front wing of a Caterham recently.

Might have been impressed if this thing had been knocked up by science club sixth formers in their sparetime on a shoestring for a national competition - as used to be the case up until the 1980s across decent schools. But when you hear they(Axon) are part of the £100m 'low carbon vehicle' beanfest of taxpayers' money the joke goes rather sour. Would like to know who or what is behind this outfit and how much they personally stand to gain when they bill the Whitehall bureaucrats for their extensive 'R&D' costs between now and the the inevitable commercial collapse circa 2011 - with all public monies written-off. Hasta la vista suckers!

Bear in mind too that as has been mentioned above coventional diesel engine 'Eco' models like the PoloBlue are already returning 60mpg and that VW Group spend's 6% of its turnover on proper, commercial, market-focused R&D alone each and every year, which equates to more than €6 billion on 2007 figures.

I don't know how the men will react to this car but I'm pretty sure the ladies will appreciate it. I definitely like it and wouldn't mind getting one once it hist the market, do you have any idea how much it will cost? As long as they are durable and I won't have to get it to an auto repair shop too often, I'll be happy to drive it.